Why are there are Circles in my mailbox…?

So Google+ is, in our view, a lot more than a social network. The social network is important because that’s what is going to create the platform. It is what is going to create the social graph for us. But the big value is that all Google products are taking advantage of that social graph and contributing to the social aspects of that platform…

They’ve made mention of the +1’s from your network showing up in Google Search, for example.